Just after 8 AM (EDT) on Tuesday, June 29, the six residents of the International Space Station (ISS) climbed into two Soyuz space capsules as an unidentified object hurtled past them at a speed of 29,000 miles per hour, missing the space station by only 1100 feet. This was only the second time in the 10 year history of people living on the space station that the crew needed to take such precautions. If the station had been hit, the crew could have quickly undocked from the ISS and returned to Earth via the space capsules.

“We believe the probability that it would hit the station was about 1 in 360,” said Lark Howorth, who leads the team at NASA that tracks the ISS’ trajectory. NASA rules call for precautions when the risk of impact is greater than 1 in 10,000. According to NASA protocol, personnel onboard the ISS are warned several days in advance of the possibility that something might come too close to the station, allowing the crew time to move the station by firing its thrusters. That has happened 12 times. This time, however, the warning came Monday evening, less than 15 hours in advance, not enough time to plan such a maneuver.

According to The New York Times, NASA estimates that for each six month period, there is a 1-in-100 chance that some or all of the space station crew might need to evacuate; most of that risk comes from the possibility of impact from debris or natural micrometeroids. Over 10 years, the current planned lifetime of the station, the cumulative risk is nearly one in five. “It’s at the level where it probably won’t happen in the lifetime of the station, but it could easily,” said Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who has become an expert on space debris. “The debris includes spent rocket stages, and sometimes over time residual fuel combines and explodes. You now no longer have a rocket stage. You have 500 pieces of shrapnel.”

Currently, there are four hams on board the ISS: Ron Garan, KF5GPO (NASA), Mike Fossum, KF5AQG (NASA), Sergei Volkov, RU3DIS (RKA), and Satoshi Furukawa, KE5DAW (JAXA). The other two cosmonauts -- Andrey Borisenko and Alexander Samokutyaev -- are not licensed.-- Thanks to The New York Times for the information.